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Finding the Fourth Proportional to 83.90, 115.64 and 61.79

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Solution

The fourth proportional to 83.90, 115.64 and 61.79 is: 85.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    83.90 : 115.64 = 61.79 : x
  2. Step 2: Convert to fraction form
    83.90/115.64 = 61.79/x
  3. Step 3: Cross multiply
    83.90x = 115.64 × 61.79
  4. Step 4: Simplify right side
    83.90x = 7,145.40
  5. Step 5: Solve for x
    x = 7,145.40/83.90
  6. Step 6: Final answer
    x = 85.17

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.